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From: Rene Herman <rene.herman@keyaccess.nl>
To: David Newall <david@davidnewall.com>
Cc: Paul Rolland <rol@as2917.net>, "H. Peter Anvin" <hpa@zytor.com>,
	Krzysztof Halasa <khc@pm.waw.pl>, Pavel Machek <pavel@ucw.cz>,
	Andi Kleen <andi@firstfloor.org>,
	Alan Cox <alan@lxorguk.ukuu.org.uk>,
	"David P. Reed" <dpreed@reed.com>,
	linux-kernel@vger.kernel.org,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	rol@witbe.net
Subject: Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops
Date: Tue, 11 Dec 2007 15:14:18 +0100	[thread overview]
Message-ID: <475E9B3A.7050403@keyaccess.nl> (raw)
In-Reply-To: <475E95A3.3070801@davidnewall.com>

On 11-12-07 14:50, David Newall wrote:

> Rene Herman wrote:

>> This particular discussion isn't about anything in general but solely 
>> about the delay an outb_p gives you on x86 since what is under 
>> discussion is not using an output to port 0x80 on that platform to 
>> generate it.
> 
> That could be true if outb_p were used only in architecture dependent

It not only could be, it _is_ true. Not using an output to port 0x80 is what 
this discussion is about.

> code, but it's not.  It's used in drivers that are supposed to run on 
> all sorts of platforms.  Why does a megaraid controller need delays on 
> i386 but not on Sparc, PowerPC, Alpha and others?  Is it buggy on most 
> platforms, or just unnecessarily slow on Intel?

The latter probably and I don't bleedin' well care. In a discussion about 
removing the out to 0x80 the only thing that is relevant is what it should 
be replaced with. Usually, "nothing" will do but generally, udelay(1) will.

>>> is needed, wouldn't you use a real delay; one that says how long it
>>> should be?
>> Thinking that _p gives a pause is perhaps too PC-centric. Why, if a delay
>>
>> Because any possible outb_p delay should be synced to the bus-clock, 
>> not to any wall-clock.
> 
> You misunderstand.  A delay can be counted in bus cycles.

No damnit, you misunderstand. I'm saying that an outb_p _should_ be defined 
in terms of the bus clock since if you want a wall-clock delay you should be 
using just that.

The _hardware_ is synced to the bus clock and therefore, having a delay 
available that is synced to the bus clock as well makes some sense. And 
again again again again not withstanding that, a udelay will still be an 
okay replacement in practice.

Rene.

  reply	other threads:[~2007-12-11 14:16 UTC|newest]

Thread overview: 125+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-12-06 22:38 RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops David P. Reed
2007-12-07  0:15 ` Alan Cox
2007-12-07 10:44 ` Andi Kleen
2007-12-07 14:50   ` David P. Reed
2007-12-05 11:10     ` Pavel Machek
2007-12-08  0:21       ` Andi Kleen
2007-12-07 14:54     ` Andi Kleen
2007-12-07 15:43       ` Rene Herman
2007-12-07 16:28         ` Rene Herman
2007-12-11  0:31           ` H. Peter Anvin
2007-12-11  5:53       ` H. Peter Anvin
2007-12-07 16:04   ` Alan Cox
2007-12-07 16:31     ` Andi Kleen
2007-12-07 17:19       ` Alan Cox
2007-12-07 18:45         ` Rene Herman
2007-12-07 18:42           ` Alan Cox
2007-12-07 19:25             ` Rene Herman
2007-12-07 21:45               ` Alan Cox
2007-12-08 19:25     ` David P. Reed
2007-12-08 19:50       ` Andi Kleen
2007-12-08 20:47         ` David P. Reed
2007-12-08 21:04           ` Alan Cox
2007-12-08 20:26       ` Alan Cox
2007-12-11  5:58         ` H. Peter Anvin
2007-12-09  5:04       ` Rene Herman
2007-12-09 13:22       ` Pavel Machek
2007-12-11 15:14       ` Lennart Sorensen
2007-12-09 12:54     ` Pavel Machek
2007-12-09 13:41       ` Dr. David Alan Gilbert
2007-12-09 15:54       ` Ondrej Zary
2007-12-09 16:59       ` Andi Kleen
2007-12-09 21:25         ` Pavel Machek
2007-12-09 22:29           ` Alan Cox
2007-12-09 23:22             ` Pavel Machek
2007-12-10 12:02               ` Alan Cox
2007-12-10  4:17           ` Rene Herman
2007-12-10 11:30             ` Krzysztof Halasa
2007-12-10 12:08               ` Rene Herman
2007-12-10 18:02               ` Ondrej Zary
2007-12-11  1:10               ` David Newall
2007-12-11  1:25                 ` H. Peter Anvin
2007-12-11  1:42                   ` David Newall
2007-12-11  1:46                     ` H. Peter Anvin
2007-12-11  1:51                     ` H. Peter Anvin
2007-12-11  7:40                     ` Paul Rolland
2007-12-11  9:50                       ` Rene Herman
2007-12-11 12:08                         ` David Newall
2007-12-11 13:16                           ` Rene Herman
2007-12-11 13:32                             ` Paul Rolland
2007-12-11 14:15                               ` Rene Herman
2007-12-11 15:28                                 ` Rene Herman
2007-12-11 15:37                                   ` Paul Rolland
2007-12-11 15:53                                     ` Rene Herman
2007-12-11 16:58                                       ` David P. Reed
2007-12-11 17:01                                         ` Rene Herman
2007-12-11 17:05                                         ` H. Peter Anvin
2007-12-11 17:32                                         ` Alan Cox
2007-12-11 19:19                                           ` David P. Reed
2007-12-11 19:36                                             ` Pavel Machek
2007-12-11 20:16                                             ` Alan Cox
2007-12-11 20:27                                             ` linux-os (Dick Johnson)
2007-12-11 20:34                                               ` Rene Herman
2007-12-11 21:03                                                 ` David P. Reed
2007-12-11 23:56                                               ` David P. Reed
2007-12-12 13:11                                                 ` linux-os (Dick Johnson)
2007-12-12 16:12                                                   ` Alan Cox
2007-12-14 14:33                                                     ` Ingo Molnar
2007-12-16 21:26                                                       ` Pavel Machek
2007-12-17  0:02                                                         ` Alan Cox
2007-12-17  0:03                                                         ` Alan Cox
2007-12-17  0:28                                                           ` Pavel Machek
2007-12-17 14:42                                                             ` Ingo Molnar
2007-12-27 10:39                                                               ` Pavel Machek
2007-12-12 19:42                                                   ` Attitude problems David P. Reed
2007-12-12 20:31                                                     ` linux-os (Dick Johnson)
2007-12-14 16:01                                                       ` linux-os (Dick Johnson)
2007-12-11 16:32                                   ` RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops John Stoffel
2007-12-11 16:40                                     ` Rene Herman
2007-12-11 13:50                             ` David Newall
2007-12-11 14:14                               ` Rene Herman [this message]
2007-12-11 14:25                               ` Alan Cox
2007-12-12 22:18                                 ` David Newall
2007-12-12 23:00                                   ` Alan Cox
2007-12-13 13:13                                     ` David P. Reed
2007-12-13 13:21                                       ` Alan Cox
2007-12-14  1:50                                         ` David P. Reed
2007-12-14 15:16                                           ` Alan Cox
2007-12-11 15:41                               ` linux-os (Dick Johnson)
2007-12-11 16:30                                 ` Andi Kleen
2007-12-11 16:50                                   ` Rene Herman
2007-12-11 17:00                                     ` David P. Reed
2007-12-11 17:04                                       ` Rene Herman
2007-12-11 17:27                                         ` Rene Herman
2007-12-11 19:18                                         ` Pavel Machek
2007-12-11 19:16                                     ` Pavel Machek
2007-12-11 19:59                                       ` Rene Herman
2007-12-11 19:59                                       ` Rene Herman
2007-12-11 20:00                                       ` Rene Herman
2007-12-11 20:00                                       ` Rene Herman
2007-12-12 20:07                                         ` More info on port 80 symptoms on MCP51 machine David P. Reed
2007-12-12 20:26                                           ` Rene Herman
2007-12-12 20:37                                             ` David P. Reed
2007-12-12 20:58                                             ` Rene Herman
2007-12-12 21:01                                               ` Alan Cox
2007-12-12 21:12                                                 ` H. Peter Anvin
2007-12-12 21:29                                                   ` Alan Cox
2007-12-15 22:34                                                   ` Allen Martin
2007-12-15 22:46                                                     ` H. Peter Anvin
2007-12-16  0:46                                                     ` David P. Reed
2007-12-12 21:05                                               ` H. Peter Anvin
2007-12-14 22:05                                                 ` Chuck Ebbert
2007-12-15  7:22                                                   ` Rene Herman
2007-12-11 13:14                     ` RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops Alan Cox
2007-12-11 13:32                       ` Andi Kleen
2007-12-11 13:47                         ` Pavel Machek
2007-12-11 13:50                           ` Andi Kleen
2007-12-14 13:33                             ` Ingo Molnar
2007-12-11  6:54                   ` Rene Herman
2007-12-11 17:01                     ` H. Peter Anvin
     [not found] <fa./27SNSh+L5T3iqFNPdHClEu+yT0@ifi.uio.no>
2007-12-07  0:23 ` Robert Hancock
2007-12-07  5:09   ` Rene Herman
2007-12-07  5:54     ` David P. Reed
2007-12-07  7:17       ` Rene Herman
2007-12-07  7:34         ` Rene Herman
2007-12-07 10:49     ` Andi Kleen

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